Introduction

These functions allow you to obtain information about classes
and instance objects. You can obtain the name of the class to
which an object belongs, as well as its member properties and
methods. Using these functions, you can find out not only the
class membership of an object, but also its parentage (i.e.
what class is the object class extending).

Please see the Objects
section of the manual for a detailed explanation of how classes and
objects are implemented and used in PHP.